Transmission



Oct. 6, 1931. E. A. THOMPSON 1,826,682

' TRANSMISSION Original Filed Aug- 2, 1926 2 Sheets-Sheet l 1 I gwwmtoz 621/ d. 9702131 1 vg? Q W Oct. 6, 1931.

\ E. A. THOMPSON TRANSMISSION 2 Sheets Sheet 2 gwmw 6722/ d. flow 01oz:

EARL Patented Oct. 6, 1931 UNITED STATES PATEN OFFICE A. THOMPSON, OF BIRMINGHAM, MICHIGAN, ASSIGNOB TO GENERAL MOTORS CORIORATION, OF DETROIT, MICHIGAN, A CORPORATION OF DELAWARE TRANSMISSION Original application filed August 2, 1926, Serial No. 126,639. Divided and an; apnlication fled 1 5m 6 whereby the number of revolutions of the 1 one train of gears to another, in transmistor vehicle transmission including'four trains,

power output shaft with respect to thoseof the power input shaft may be varied step by step.

The difliculties incident to changing from sions of this type, unless the gears or other toothed elements to be intermeshed are first caused to rotate at substantially equal speeds are well known. A geared change speed transmission for motor vehicles equipped with means for pre-equalizing tooth speeds of elements to be intermeshed is disclosed 'and claimed in mv application Serial No.

126,639, filed August 2, 1926; this application is a division thereof.

In this application there are shown an described, as in the parent application, a moby proper selection among which the'output shaft may be rotated relatively to the input shaft in the same direction (forward) at any one of three different speeds, and in the reverse direction at one speed.

I have applied means, herein termed synchronizing devices. adapted to bring the toothed elements of high and second speed trains, only, to approximately the same tooth speed before intermeshing them. Low speed and reverse trains'are used less frequently than high and second, and are normally coupled when the car is'standing still. Therefore there is no practical need for synchronizing devices associated with low and reverse trains.

Second speed spline shaft (output shaft) gear, in accordance with my invention, is in constant mesh with its coacting countershaft gear and is provided with clutch teeth whereby said gear is adapted to be locked to the spline shaft by a selective slidable double ended jaw clutch or coupling element when the latter is moved rearward to transmit the power of the engine in second speed. When the sliding jaw clutch element is movedforward its front end teeth mesh with the teeth Serial No. 529,700. I

or jaws of a coacting clutch element on the of the jaw elements to be engaged prior to intermeshing. By reason of the use of jaw clutchesselectively operated instead of slidingly intermeshable gears for the high and second speed trains, axial movement of the intermeshable elements need be less than is' considered necessary in intermeshing slidable gears directly. The axial movement necessary to engage and disengage the conical friction clutch parts here utilized as synchronizing devices need also be much less' than is needed to shift sliding gears into and out of mesh. Also a relatively large force isrequired to press together the friction synchronizing devices'strongly enough to effect synchronization in the brief time permitted for this in the shifting operation.

First, or low, and reverse trains are selected according to tliis invention by sliding a gear axially on the spline shaft into and out of mesh with coacting low speed counter shaft gear or reverse idler; The axial movement of the slidable gear is greater than that i of the coupling element for selecting high and second speeds, and requires a lesser amount of force than is necessary to effect synchronization of high and second speed trains. i

In accordance with thisinvention alsofithe several trains are selected and intermeshed by a shift lever which is operated precisely in the manner customary with ordinary sliding gear transmissions. The shift lever is moved in the usual manner to interlock with one slide for shifting to higlf or second, and to interlock with another slide for shifting to low orreverse. lever has substantially the same amplitude of movement in making all shifts, but operates with a higher mechanical advantage in coupling the two trains that include the chronizing devices than in coupling the ot er two including the gears that are directly coupled by sliding one into mesh with .'another. Thus the operator,"by exerting the The handle of the shift same amount of force upon the handle of the shift lever and giving it the same amplitude rof movement may apply the relatively large force and shorter movement to one slide requiredio synchronize high and second speeds, or the relatively small force and longer move-v ment-to the other slide for shifting the slidable gear to couple the trains not provided with synchronizing devices. This construction and disposition of the gear trainsand controls is of distinct advantage. because the changes of speed may be efiected by the driver without the disconcertion likely to result from having to apply greater, (and perhaps inadequate) force.'in makingthe shifts into high and second than into low and reverse :or from having to move the shift lever handle through a greater are in some shifts than in others. Variations in length of shift lever handle movements are awkward also because of the limited'space in front of the drivers seat of the usual motor vehicle within which the shift lever moves. 25 In the accompanving drawin s in which like referencecharacters are used to indicate like parts throughout the several views:

Fig. 1 is a longitudinal sectional view of a constituting the power output or driven shaft.

and ,4 the usual counter shaft. Clutch shaft 2 is supported and rotates-in roller bearin 5 at the power input end of the housing and driven shaft 3 in hall bearings 6 at the rear or power output end of the housing. The forward end of driven shaft 3 is reduced as shown at 7 and piloted in roller bearings 8 within a bore in clutch shaft 2. Clutch shaft 2 terminates rearward in a hollowed enlargement 9 which surrounds the forward ends 0 of the splines on shaft 3. and is provided interiorly with a conical friction-surfaced recess 10 and with an annular row of interior clutch teeth 11 just rearward of the conical clutch surface. Enlarged part 9 isformed exteriorly with the groove 12 for a purpose that will appear presently. ltigidly secured to spline shaft 3 within the conical recess 10 is an externally conical member 13 the surface of which is normally free of the internal conical surface'of the recessed member but' shaft 2 is longitudinally slidable, as hereinafterdescribed, sov as to effect a frictional engagement between said two conical surfaces whereby to couple frictionally shafts 2 and 31' Agear 14 rotated by shaft 2 meshes with gear-.15 rigid withcounter shaft 4. Gears aeaaeea 16, 17 and 18 are also rigid with the counter shaft, gear 18 meshing with reverse idler 19. Gear 20, splined slidably on'shaft 3, may be slid into mesh with gear 17 to couple the low ical bearing and clutch member rigid with shaft 3 afiords a bearing surfacefor said gear 25 to rotate upon or an element of a friction clutch to cooperate with said gear. Ahub like hollow extension 26 rigid with gear 25 is provided exteriorly with a groove 27 and interiorly with a row of clutch teeth 28.

Gear 25 maybe locked to shaft 3 by a slidable coupling or clutch member 29, which is provided with an external annular groove 33 and external teeth on each end or on opposite sides of the groove. If coupling 29 be moved forward, or to the right as shown 1n Fig. 1, theteeth 30 may be meshed with the teeth 11 rigid with shaft 2 and thereby lock shafts 2 and 3 to rotate in unison; if moved rearward or to the left of Fig. 1, teeth 30 Y may be meshed with teeth 28 rigid with gear 25 and thereby lock gear 25 to shaft 3. A

'forked arm 31 carried by shifter rod 32 engages in groove 33 and slides coupling 29 in one direction or the other as the slide .or shifter rod 32 is moved. Shifter rod 32 may be moved by shift lever 24,..which may be interlocked at will with either shift rod 23 or 32, according to whether it is desired to conple low or reverse-trains on the one hand or, on the other hand, high or intermediate.

Before coupling member 29 interlocks with either the coacting toothedelements of shaft 2 or gear 25 to positively couple, in the former case shafts 2 and 3,a'nd in the latter gear 25' and shaft 3. said shafts 2 and 3, or said gear 25 and'shaft 3'are firstvfrictionally coupledby engagement .of the friction members described, in order to bring the parts to be later positively coupled to synchronous speeds. To accomplish the frictional coupling, yokes 34 and35 are provided to -move axially, respectively, the shaft 2 to. an extent suficient "to efiect engagement of the internal conical surface 10 with the external conical surface of the member 13, and the gear 25 suficiently to efi'ect a frictional driving engagement with w the member 25'. As the two yokes and coopcrating. elements are similar a description of one will sufice for both.

Each yoke comprises two limbs pivotally mounted on oppositely disposed fulcrum pins posite direction by one or more springs. The

' limbs of the yokes project below the fulcrum pins to form the work arms which support thrust pins 37 carrying, pivotally, thrust blocks 38. The blocks 38 on yoke are disposed in the circumferential groove 27' of gear 25, while those on yoke 34 are disposed in circumferential groove 12 of the enlarged end portion of shaft 2.

The yokes illustrated constitute levers of the first order having power arms much longer than their work arms and therefore operate the friction clutches with very considerable mechanical advantage. Themeans whereby sliding of shifter rod 32 operates the yokes will be described first with respect to one of them. Fig. 2 illustrates with res to yoke 35 a drilled and counter bored diameter and receives a piston 410 on the lower end of. plunger 41, dividing thc'recess into chamber 39 abovethe piston and chamber 40 below it. A small groove 48 in the side of piston 41a forms a restricted communica-,

tion between the two chambers. The outer or upper end of the recess is threaded to receive a threadedcap 44 having an axially extend-- I ing orifice which guides an extension 43' of;

said plunger, the preferably semispherical end of which is adapted to yieldably engage or interlock with suitable shoulders on shift rod 32. Plunger 41 is also provided with a flange 42 which may engage the inner end of cap 44 and thereby limitthe extent of move-. ment of the plunger outward. A coil compression spring 45 within the bore exerts pressure between the shoulder 46 .of the counter hereof the recess, and said flange42, thus tending to keep the end of extension 43 pressedagainst the shift rod 32. A passage 47 having a flaring outer end communicates between chamber 39 and the space within the housing. Oil may be introduced through the passage 47 into the chamber 39 whence it will flow throughfthe groove 48 into chamber 40. en the chamber 40 is filled'with oil the described mechanism functions as a liquid brake 'or dash pot. The chamber. is kept filled with oil during operation by the splash from the oving mechanism within the housing.

Shift rod 32, as most plainly shown in Fig. 3, isprovided with spaced apart longitually elongated recesses49 and 50 each having a plane surface terminating at the end nearest the other recess in a shoulder 49a,

5012, respectively, each shoulder merging into the plane surface in a curve preferably formed on a radius equal to the radius of the semi-spherical end of a plunger extension 43. Shifter arm 31 is secured to rod 32 midway between said shoulders 49a and 50a. Extending from shoulder 49a toward the shifter arm 32 is an inclined surface 51, terminating in a rounded recess. A like inclined surface 53 extends from shoulder 50a toward the shifter arm and terminates in recess 54. Y

A contractile coil springv 55 exerts its elasticity'to urge the yokes 34 and 35 toward one another. The ends of the spring are attached to stop flanges 56 which coact with cushioned stops 90, carried by a bracket 88 on the housing. ''.?Bracket- 88 is counterbored on opposite sides'to form opposed cylinder bores 89. Stops 90 constitute pistons sliding in the bore which are elastically positioned by springs 91. Holes 92 connect the cylinder bores 89. with a pan-like depression 93 in theupperface of bracket 88. The splash of oil occurring during operation keeps the pan and cylinder bores suppl ed with oil. Thus stops 90 act as fluid brakes to cushion and silence the impact of either of the yokes 34 or 35. recess the lower end of which is reduced in As illustrated in the drawings the construction and relative arrangement of the movable clutches and gears of the transmission assembly. the shifter rods and the shifter lever, are such that the amplitude of movement of the movable elements of the selec-- tive clutches associated with the h gh ahd second speed gear trains necessary to couple them is less, than the amplitude of movement necessary to couple the low speed andreverse 2 trains; consequently the amplitude of movement of shifter rod 32. by, which coupling member 29 and associated movable friction clutch elements are moved, needs to be less than that 'of shifter rod ,23 by which sliding gear 20 is moved. Furthermore, a larger force is required to shift into high and second than to shift into low and reverse because of the necessity of forcing the friction clutch elements intodriving engagement adequate to insure svnchronization within the period of time permitted for shifting. The lesser amplitude of movement and greater force necessary in shifting to high and secondspeed trains is obtained by means of the con-,

struction and arrangement shown. Reference to Figs. 1 and 2 shows that shifter rods 32 and 23 are provided, respectively, with brief notches 32aand 23a adapted to interlock I lever 24 are such that the range of movement of the handle 24% of said lever is approximately the same for all shifts, and the me chanical advantage applicable to shift rod 32 enables a greater force to be applied in synchronizing and coupling the elements of high and second speed trains than in coupling low and reverse without any greater movement of the handle or the exercise of greater muscular effort by the operator. lit will be understood that the shift lever 24 is manipulated by the operator in the manner usual in conventional sliding gear variable speed transmissions. A fixednotched rail, or equivalent, (not shown) of any usual form is arranged to have its notch register with the notches 23a and 32a of the shifter rods when all trains are uncoupled, the lower end of shifter lever 24 may then engage in the notch of the fixed rail (neutral position). In this condition none of the trainscan be coupled as they are locked in neutral. By moving the lower end of shifter lever to the left (Fig. 2) shifter rod 32 may be interlocked with the shift lever so that either the high or second speed trains can be-coupled or by moving said lever in the opposite direction it may be interlocked with shifter rod 23 so that low or reverse trains may be coupled.

In the drawings the parts are shown in neutral position. To shift into low speed or into reverse gear the gear 20 is operated from the shifter rod 23 in the usual manner. When it is desired to shift into secondlgear,

the shift lever 24 is operated to move the shifter rod 32 to the right as shown in Fig.

3 and tothe left as shown in Fig. 1, this movement of the shifter rod causing shoulder 49a at that end of the recess 49 adjacent the beveled surface 51 to engage the upper end of the extension 43 of the plunger 41 and rock the yoke 35 sothat the thrust blocks 38 will force the gear 25 into tight frictional engagement with the conical member 25' so that the gear will rotate with the conical member and establish a ,synchonized condition between the gear 25 and the coupling 29 in or der that the teeth 28 of the gear may be readily meshed with the teeth 30 of the coupling without clash. The resistance developed by the gear 25 being placed into tight frictional engagement with the conical member 25 will cause the plunger 41 to be lowered against action of the coiled spring 45 this allowing the end of the extension 43 to pass from engagement with the end ofthe recess 49 and to pass over the inclined surface 51 to position for engagement in the rounded recess 52. In addition to the pressure of the spring 45 on the plunger 41 there will be a hydraulic pressure within the chamber 40 and as the plunger is lowered the lubricant within the chamber 40 will pass through the groove 48 to the opposite side of the enlarged lower end of the plunger and into the cham ber 39. llhe hydraulic pressure retards the downward movement of the plunger and if teaaeea hold the upper end of the plunger in engagement with the end of the recess in the shifter rod a suficient length of time to allow'for proper synchronizing. This same action increases the pressure to rock the yoke and force the gear into engagement more tightly with its associated conical member. Resistance to the movement of the operating means is increased as the speed of the movement of said operating means is, increased. lln other words the resistance varies according to the rate of movement of the-operating means.

It will be understood that the hydraulic pressure may be increased or decreased by varying the diameter of the plunger, the size of the chamber 40 in which the end of the plunger operates, or the size of the groove 48. 'lfhe engagement shoulder.49a at the end of-the recess'49 with the end of the extension 43 of the plunger operates to restrain the shifting of the shift rod to allow time for synchronization and as just described the dash pot effect of chamber 40 and plunger 41 further augments this restraint for controllin the synchronizing time element 'as' desire lit will be understood that the hydraulic pres sure developed in the chamber 40 will vary with the viscosity of the transmission oil therein and inasmuch as the viscosity of the oil varies from time to time due to changes in temperature the retarding efiect on the depression of the plunger 41 will be increased as the viscosity of the oil increases so that, as for example in cold weather, the transmission oil becomes heavy and consequently a greater-power is necessary to synchronize the gears. The hydraulic action will furnish ice means'for allowing more time for synchroni- 4 zation as well as increasing the synchronizing effect. As the extension 43 of the plunger passes from engagement with the end of the recess 49 the coiled spring 55 tends to draw the yoke towards its original or normal position against the stop 90 and this movement removes the restraint on the shifter rod 32 and allows the latter to be accelerated to move the coupling member 29 into engaging position with the teeth 28 of the gear 25 this movement being further augmented by the'end of the extension 48 of the plunger bearing against the inclined surface 51. The

engagement of the extension in the rounded recess 52 holds the shifter 'rod in its shifted position. In the event that the teeth of the coupling member 29 abut the internal teeth 28 of the gear 25 said gear 25 will be jarred free of or disengaged from its engagement with the conical member 25' so as to allow the gear 25 to have a slight rotary movement in order that the teeth28 thereof may be meshed with the teeth 01? the coupling member 29.

The angle of the conical member 25 and its corresponding or cooperating gear 25 is such that when these two parts are brought into tight frictional engagement they will continue to transmit a substantially normal amount of torque without the aid of axial pressure from the yoke tending to hold them in tight 'frictional engagement while at the same time the gear 25 can be released from frictionalengagement with the conical member 25 by the normal amount of axial pressure produced by the spring when augmented by. a slight blow from the coupling member 29. What has been said relative to the angle of the conical member 25' and its associated gear 25 is applicable to the conical member 13 and its associated member 10 formed on the inner'end of the shaft'2.

ln going from second gear to high gear it will be understood that theshifter rod 32 will be moved in the o posite direction and operate the yoke 3d, an its associated parts in the same manner as has been described in operatingtheyoke 35,the yoke 34 being rocked through engagement of the extension 43 of the plunger 41 of that yoke with the shoulder 50a en the couplingmember is neutral position it is spaced suficiently, far away from the members with which it is to be meshed so that before the teeth of the coupling member mesh with the teeth of the cooperating power member there, is 'suficient movement of the shifter rod to efiect engagement of the synchronizing members, and to allow the extension 43 of the plunger carried by the yoke to pass from engagement with the end of the recess with which it is normally engaged in neutral position.

In Fig. 3 the yokes 3d and 35 are illustrated as being drawn towards one another by means of the coiled spring 55. Stop plungers 90, sliding in cylinder bores 89 vwithin a bracket 88 formed on or-secured to the casing or housing 1 stop the yokes in neutral position. The plungers are pressed outward by means of the coiled springs 91 and the outer ends of the plungers are normally in enormed on the yokes; The upper surface of the bracket 88 is dished or recessed as shown at 93 to form a reservoir for the transmission oil. Openings 92 extend from the dished orrecessed portion 93 and communicate with the recemed cylinder'bores 89 so that when the plungers 90 are in their outermost positions oil will pass into the recessed cylinders 89 and form' a cushion against the return of the plungers to their normal positions. This cushioningaction does away with any noise incident to the return of the yokes to their normal positions. I

Having fully describedmy invention what I claim as new and desire to secure by Letters Patent is:

1. A variable speed-ratio transmission mechanism composed of plural gear trains, at least one of which comprises intermeshable elements and another comprises both intermeshable and synchronizing elements; means for selectively coupling-either of said trains including a manual control device, the operative connections between said manual control device and the synchronizing and intermeshable' elements of the latter mentioned train possessing a greater mechanical advantage than the operative connections between said manual control device and the intermeshable elements of'said former mentioned train.

2. A variable s peed-ratio transmission mechanism composed of plural gear trains at least one of which comprises intermeshab'le elements and another comprises both intermeshable and synchronizing elements; said intermeshable and synchronizing elements of the latter mentioned train having a shorter range of coupling and uncouplin .movement than the intermeshable elements 0 the former mentioned train; means for selectively coupling either of said trains including a manual control device, the operative connections be- 7 tween said manual control device and the synchronizing and intermeshable elementsof the latter mentioned train possessing a greater mechanical advantage than the operative connections between said manual control device and the intermeshable elements of said former mentioned train. v

3. A variable speed-ratio transmission mechanism composed of plural gear trains'at least one of which comprises intermeshable elements and another both intermeshable and roe its

synchronizing elements means for selectively latter mentioned 'trainbeing engageable by said lever at a point nearer the fulcrum than the point of engagement with said lever of the o rativc connections between said lever and ;t e 'intermeshable elements of said former --mentionedtrain, s

4. A variable speed-ratio transmission mechanism composed of plural gear trains at least one of which comprises intermesh'able elements and another comprises both interi meshable and synchronizing elements, said intermeshable and synchronizing elements of the latter'mentioned train having'a shorter range of coupling and uncoupling movement than the intermeshable elements of the former mentioned train; means for selectivelycoupling either of said trains including a manually operable shift lever, the operative connections between said lever and the synchrorange of movement of the intermeshable' v members of the "former mentioned train substantially equals the ratio of the movement of the respective points of engagement of said lever with the operative connections to the ename clutch element is engageable at a oint nearer the fulcrum of the lever than t e shiftable member for the slidable gear.

8. A variable speed-ratio transmission mechanism composed of a power input and power output member, a. countershaft, and plural gear trains associated therewith; means for couplin said trainsincluding pairs of intermeshable toothed elements one element of each pair being slidable into and out of mesh with the other; separate shifter members operatively connected with said slidable toothed elements, respectively; a

manual control lever adapted to selectively operate each shifter member, selectively engageable means on said shifter members arranged with respect to the shifter lever in positionssuch that the shifter member for one slidable toothed element is engageable at a point nearer the fulcrum of the lever than the other.-. t r 1 In testimony .whereof'll athx my. signature,

' EARL A. THUMPSON. V

respective trains whereby the handle end of i said lever moves in substantially equal. arcs during the operation of coupling either train.

6. A- variable spee -ratio. transmission mechanism composed of apower input, power output and counter shaft and plural gear trains associated with said shafts; means for coupling :at least one of said trains including coacting jaw clutch elements one of which is slidable axially into and out of mesh with the other; means for coupling another oisaid trains comprising intermeshable gears on counter-shaft and power output shaft one of which is slidable into and out of mesh with the other; means for selectively meshing said clutch elements and said ear elements including a manually operab e shift lever, the

- operative connections between said lever and the slidable jawclutch element bein'gnearer the fulcrum of thelever than the orative connections between said. lever and te slid-- able" gear.

7. A variable speed-ratio transmission mechanism composed of a power input and power outputlmember', a counter shaft and plural gear trains associated therewith; means for coupling at least one of said trains including j aw clutch elements one of which is slidable into and outof mesh with the other;

means forcoupl-ing another of said trains comprising intermeshabl'e gears one of which is slidable into and out of mesh withthe other; separate shifter members operatively connected with said slidable clutchelement a manual and said slidable gear respectively control lever adapted to selectively operate -each shifter member, selectively engageanle means on said shifter members arranged with respect to the shifter lever in positions such that the shifter member for the slidable no v 

